Fine cloisonne

ABSTRACT

PRODUCING FINE CLOISONNE JEWELRIES FOR INSTANCE HIGHCLASS LAPEL PINS FROM A BASE OF COPPER OR BRASS BY PLATING SPECIAL SILVER ALLOY ON THE BASE BEFORE COATING WITH CLOISONNE.

June 27, 1972 SADAlCHl KUWANO 3,672,967

FINE CLOISONNE/ Filed May 28, 1970 FIGB f j z TV 3? Y 4-" United States Patent 3,672,967 FINE CLOISONNE Sadaichi Kuwano, 72, l-chome, Saikudanicho, Tennojiku, Osaka, Japan Filed May 28, 1970, Ser. No. 41,245 Int. Cl. C23f 17/00 US. Cl. 204-38 C 4 Claims ABSTRACT OF THE DISCLOSURE Producing fine cloisonn jewelries for instance highclass lapel pins from a base of copper or brass by plating special silver alloy on the base before coating with cloisonn.

The present invention relates to a fine cloisonnware and a method to produce such, and in its more particular aspects it has to do with the application of this method to production of high-class cloisonn wares such as fine finished jewelries from base materials, such as of copper, brass, or nickel silver, etc.

Fine cloisonnwares may often be appreciated for highclass jewelries. conventionally in production of cloisonnware a base of copper or silver is coated with a layer of cloisonn at 700 to 800 C. In this case, a copper base shows inferior reddish-brown luster in the finished article and thus fails to provide sufiicient fineness for jewelries. A silver base shows satisfactory noble fine luster in the finished article but the cost of production is substantially high due to a considerably high percentage of material loss in cutting the base to suitable shapes and pieces of jewelries for instance lapel pins, cuff links, tie bars, emblems, brooches, pendants and etc. Such high percentage of material loss will increase the cost of production quite substantially in case of precious material such as silver.

A major object of the invention is to provide a fine cloisonnware for high-class jewelries at a substantially low cost of production.

A more specific object of the invention is to produce a fine cloisonnware from a base of copper or brass etc. by plating silver alloy on the base and then coating cloisonn on the silver alloy.

Other objects and advantages of the invention will be more fully understood from the following description in reference to the accompanying drawings in which:

FIG. 1 is a fragmentary cross section of a cloisonnware produced in accordance with the invention;

FIG. 2 is a fragmentary cross section of a cloisonnware produced conventionally from a base of silver; and

FIG. 3 is a fragmentary cross section of a cloisonnware produced experimentally by the inventor.

Initially the inventor carried out an experiment in which ten base of copper for jewelries were silver-plated in electrolytic baths of known kinds for silver plating, before they were coated with cloisonn; five of them were treated in an electrolytic bath composed as per Table l with 0.3 a./dm. of current density, and therest of them were treated in another electrolytic bath composed as per Table 2 with 0.3 a./dm. of current density.

Patented June 27, 1972 After they were coated with cloisonn, all the ten lapel pins turned out to be cracked on the surfaces. Their cross sections as examined through a magnifying glass were as shown in FIG. 3, where silver layers 2" plated on both sides of a copper base 1 are swollen and a cloisonn layer 3 above the silver layer is cracked as at 3'. In fact, the silver layers were swollen because they failed to stand the heat of 700 C. to 800 C. usually required in cloisonn finishing.

Then the inventor tried to provide a silver layer sufliciently endurable against such heat and therefore free of being swollen in spite of the required heat in cloisonn finishing. For this purpose the inventor found it useful to add a nickel salt K Ni(ON) -H O in an electrolytic bath composed as per Table l or 2. However, the addition of such nickel salt resulted in an excessive increase in concentration of the bath. Then, for instance in Table 1, the inventor decreased NaCN from 25 grams to 5 grams correspondingly as K Ni(CN) -H O was increased from 10 grams to 30 grams gradually, and the results were corresponding decrease of cracks on the cloisonn-finished surfaces, but the cracks were not eliminated completely.

Now the inventor prepared an electrolytic bath of novel kind composed as per Table 3 with 0.3 a./dm. of current density, where NaCN was completely replaced by K Ni(CN) -H O, and also Na CO was replaced by K CO A number of copper bases for lapel pins were plated with silver-nickel alloy in the above-prepared electrolytic bath before they were coated with cloisonn. After they were coated with cloisonn, all the lapel pins turned out to be free of cracks completely on the surfaces in spite of ex posure to heat of 700 C. to 800 C. This is shown in FIG. 1, where silver-nickel layers 2' and 2 plated on both sides of a copper ground 1 are not swollen at all but in quite a satisfactory condition; and a cloisonn layer 3 above the silver-nickel layers are not cracked at all but in quite as satisfactory a condition as in the case of FIG. 2 where a cloisonn layer 3 is coated on a silver ground 2 by known practice.

The cloisonn lapel pins thus produced from bases of copper or brass all show satisfactory noble fine luster quite suitable and desirable for high-class jewelries yet the cost of production is sufficiently low since they are produced from bases of copper or brass etc. which are much more inexpensive than silver.

Since certain changes and modifications may be made in the invention, it is intended that the foregoing shall be construed in a descriptive rather than in a limiting sense.

What is claimed is:

1. Method of producing fine cloisonn jewelry having a base of copper or brass, comprising the steps of electroplating at least one surface of said base with a silver-nickel alloy in an electrolytic bath comprising AgCN and K Ni(CN) -H O; and

coating a layer of cloisonn on the plated silver-nickel alloy.

2. Method of claim 1, wherein said bath further comprises K CO and water.

3. Method of claim 1, wherein said-cloisonn surface is heated to a temperature within the range of from 700 C. to 800 C.

4. Method of claim 1, wherein direct current is applied at a current density of about 0.3 a./dm.

References Cited UNITED STATES PATENTS 5 The Electrodeposition of Alloys by Brenner, vol. I, Academic Press, 1963, p. 617.

The Metal Industry by Helmle, 1943, pp. 154-156.

JOHN H. MACK, Primary Examiner R. L. ANDREWS, Assistant Examiner US. Cl. X.R. 

